Also likely is that part of the genome that produces toxins in one part of the plant that isn't normally eaten gets turned on in edible part. For example: aspa

Also likely is that part of the genome that produces toxins in one part of the plant that isn't normally eaten gets turned on in edible part. For example: asparagus berries are toxic, but the toxin doesn't appear in the stalk. The mechanism to produce the toxic chemical is there, just turned off in those cells. Enabling it is the sort of thing that small mutations might do.